Heat transfer fluids and corrosion inhibitor formulations for use thereof

ABSTRACT

Heat transfer fluid concentrates include: a freezing point depressant, water, or a combination thereof; a carboxylate; an inorganic phosphate; an azole compound; calcium ions; and a water-soluble polymer. Ready-to-use heat transfer fluids and methods for preventing corrosion in heat transfer systems are described.

RELATED APPLICATIONS

This is a continuation-in-part of prior application Ser. No. 14/087,796, filed Nov. 22, 2013 (U.S. Pat. No. 9,145,613), which in turn is a continuation of prior application Ser. No. 13/606,452, filed Sep. 7, 2012 (U.S. Pat. No. 8,617,416). The entire contents of both of these documents are incorporated herein by reference.

TECHNICAL FIELD

The present teachings relate generally to heat transfer fluids and, in some embodiments, to heat transfer fluids for inhibiting corrosion in heat transfer systems.

BACKGROUND

Modern vehicle engines may use a heat transfer fluid (e.g., liquid coolant) to provide long-lasting, year-round protection of their cooling systems. A key function of heat transfer fluids is to transfer excess heat from an engine to a radiator for dissipation. Efficient heat transfer and control of engine temperature leads to efficient fuel economy and lubrication, and may prevent engine failures due to freeze-up, boiling-over, or over-heating. Ideally, engine coolant may also serve to provide corrosion protection of cooling system metals (e.g., over a range of different temperature and operating conditions).

Common corrosion-related problems that may arise in automotive cooling systems include: (1) cavitation corrosion and rusting of cylinder heads and cylinder blocks; (2) seal leakage, bellows seal failure, and cavitation corrosion in water pumps; (3) solder bloom, scale and deposit formation, and pitting in radiators and heater cores; (4) thermostat sticking; and/or (5) crevice corrosion at hose necks. In addition, erosion-corrosion, galvanic corrosion, under-deposit corrosion, and/or stray-current corrosion may occur at susceptible locations in a cooling system depending on conditions.

Different kinds of metals may be used to fabricate the various parts of a cooling system. By way of example, cast iron and cast aluminum alloys may be used for cylinder blocks, cylinder heads, intake manifolds, coolant pumps, and power electronic device enclosures; wrought aluminum and copper alloys may be used for radiators and heater cores; solders may be used to join the components of brass or copper radiators or heater cores; steel may be used for cylinder head gaskets and for small components such as freeze plugs, coolant pump housing enclosures, and coolant pump impellers; and copper alloys may be used in thermostats.

Corrosion protection of components manufactured from aluminum or aluminum alloys (e.g., engine block, cylinder head, water pump, heat exchangers, and the like), corrosion protection of heat transfer system components produced by a controlled atmosphere brazing (CAB) process (e.g., heat exchangers), and corrosion protection at high temperature (e.g., in cooling systems for vehicles equipped with exhaust gas recirculation or EGR) are of particular interest.

SUMMARY

The scope of the present invention is defined solely by the appended claims, and is not affected to any degree by the statements within this summary.

By way of introduction, a first heat transfer fluid concentrate in accordance with the present teachings includes (a) a freezing point depressant, water, or a combination thereof; (b) a carboxylate; (c) an inorganic phosphate; (d) an azole compound; (e) calcium ions in a concentration ranging from about 1 mg/L to about 60 mg/L based on a total weight of the heat transfer fluid concentrate; and (f) a water-soluble polymer.

A second heat transfer fluid concentrate in accordance with the present teachings includes (a) a freezing point depressant, water, or a combination thereof, wherein the freezing point depressant is present in an amount ranging from about 15 wt. % to about 99% wt. % based on a total weight of the heat transfer fluid concentrate; (b) a C₆-C₂₀ carboxylate in an amount ranging from about 1 wt. % to about 10 wt. % based on the total weight of the heat transfer fluid concentrate, wherein the C₆-C₂₀ carboxylate is selected from the group consisting of an aliphatic mono-carboxylate, an aliphatic di-carboxylate, an aromatic mono-carboxylate, an aromatic di-carboxylate, and a combination thereof; (c) an inorganic phosphate selected from the group consisting of an orthophosphate, phosphoric acid, and a combination thereof, wherein a phosphate ion concentration in the heat transfer fluid concentrate ranges from about 0.002 wt. % to about 5 wt. % based on the total weight of the heat transfer fluid; (d) an azole compound in an amount from about 0.01 wt. % to about 3 wt. % based on the total weight of the heat transfer fluid concentrate; (e) calcium ions in a concentration ranging from about 1 mg/L to about 60 mg/L based on a total weight of the heat transfer fluid concentrate; and (f) an acrylate-based polymer. A ratio of a concentration of the acrylate-based polymer to the concentration of the calcium ions is greater than about 4 and less than about 110.

A ready-to-use heat transfer fluid in accordance with the present teachings includes water and a heat transfer fluid concentrate of a type described above. The heat transfer fluid concentrate is present in an amount ranging from about 40 vol. % to about 60 vol. % based on a total volume of the heat transfer fluid.

A method in accordance with the present teachings for preventing corrosion in a heat transfer system includes contacting at least a portion of the heat transfer system with a heat transfer fluid of a type described above.

DETAILED DESCRIPTION

In accordance with the present teachings, heat transfer fluid concentrates and ready-to-use heat transfer fluids derived from heat transfer fluid concentrates (e.g., by dilution with water) exhibit a synergistic effect between the components of the formulation with respect to corrosion inhibition. As further described below, the synergistic heat transfer fluid concentrates and ready-to-use heat transfer fluids derived therefrom contain calcium ions (e.g., such as may be derived from one or more water-soluble calcium salts).

It is to be understood that elements and features of the various representative embodiments described below may be combined in different ways to produce new embodiments that likewise fall within the scope of the present teachings.

By way of general introduction, in a heat transfer fluid concentrate comprising a freezing point depressant (e.g., ethylene glycol), water, a carboxylate, an inorganic phosphate, and an azole compound, a synergistic effect is observed between calcium ions and a water-soluble polymer (e.g., an acrylate-based polymer), as shown by corrosion test data and storage test data. In some embodiments, the optimal performance is observed when a concentration of the calcium ions ranges from about 1 mg/L to about 60 mg/L based on a total weight of the heat transfer fluid concentrate, and/or when a ratio of active acrylate-based polymer concentration to the calcium ion concentration in the heat transfer fluid concentrate is greater than about 4 and less than about 110.

In some embodiments, a heat transfer fluid concentrate in accordance with the present teachings includes: a freezing point depressant, water, or a combination thereof; a carboxylate; an inorganic phosphate; an azole compound; calcium ions; and a water-soluble polymer.

Heat transfer fluid concentrates in accordance with the present teachings may include a freezing point depressant. Representative freezing point depressants suitable for use in a heat transfer fluid concentrate in accordance with the present teachings include but are not limited to alcohol and mixture of alcohols (e.g., monohydric alcohols, polyhydric alcohols, and mixtures thereof). Representative alcohols for use as freezing point depressants include but are not limited to methanol, ethanol, propanol, butanol, furfurol, furfuryl alcohol, tetrahydrofurfuryl alcohol, ethoxylated furfuryl alcohol, ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, dipropylene glycol, butylene glycol, glycerol, glycerol-1,2-dimethyl ether, glycerol-1,3-dimethyl ether, monoethylether of glycerol, sorbitol, 1,2,6-hexanetriol, trimethylopropane, alkoxy alkanols (e.g., methoxyethanol), and the like, and combinations thereof.

In some embodiments, the freezing point depressant comprises an alcohol which, in some embodiments, is selected from the group consisting of ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, glycerol, and a combination thereof. In some embodiments, a heat transfer fluid concentrate in accordance with the present teachings contains a glycol freezing point depressant. The concentration of freezing point depressant may vary depending on the application. In some embodiments, the concentration of the freezing point depressant ranges from about 15 wt. % to about 99% wt. % based on the total weight of the heat transfer fluid concentrate. In other embodiments, the concentration of the freezing point depressant ranges from about 20 wt. % to about 98% wt. % based on the total weight of the heat transfer fluid concentrate. In further embodiments, the concentration of the freezing point depressant ranges from about 20 wt. % to about 96% wt. % based on the total weight of the heat transfer fluid concentrate.

Heat transfer fluid concentrates in accordance with the present teachings may include water in addition to, or as an alternative to, a freezing point depressant. Ready-to-use heat transfer fluids derived from heat transfer fluid concentrates (e.g., by dilution) typically contain water. In some embodiments, a heat transfer fluid concentrate in accordance with the present teachings that contains a freezing point depressant may be diluted with water to a 40 vol. % to 60 vol. % solution.

The type of water used in accordance with the present teachings is not restricted. However, in some embodiments, the water used in a heat transfer fluid concentrate and/or a heat transfer fluid in accordance with the present teachings includes de-ionized water, de-mineralized water, softened water, or a combination thereof. In some embodiments, a hardness of the water due to CaCO₃ is less than about 20 ppm. In other embodiments, an electrical conductivity of the water is less than about 300 μS/cm. In further embodiments, a hardness of the water due to CaCO₃ is less than about 20 ppm and an electrical conductivity of the water is less than about 300 μS/cm.

Heat transfer fluid concentrates in accordance with the present teachings may further include one or a plurality of carboxylates. As used herein, the term “carboxylate” is inclusive of carboxylic acid, salts thereof, and combinations of one or more carboxylic acids and one or more carboxylic acid salts. The carboxylate may include a single or multiple carboxyl groups and may be linear or branched. It is expressly contemplated that combinations of carboxylates may be used and such combinations are encompassed by the terms “carboxylate” and “carboxylic acid”. In some embodiments, a carboxylate in accordance with the present teachings has from 6 to 20 carbon atoms. The carboxylate may be aliphatic, aromatic, or a combination of both. In some embodiments, a carboxylate in accordance with the present teachings consists of carbon, hydrogen, and oxygen and is free of non-oxygen heteroatoms. Representative aliphatic carboxylates for use in accordance with the present teachings include but are not limited to 2-ethyl hexanoic acid, hexanoic acid, heptanoic acid, octanoic acid, neodecanoic acid, decanoic acid, nonanoic acid, isoheptanoic acid, dodecanoic acid, sebacic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, dodecanedioic acid, and/or the like, and combinations thereof. Representative aromatic carboxylates include but are not limited to benzoic acid, toluic acid (methylbenzoic acid), tert-butyl benzoic acid, alkoxy benzoic acid (e.g., methoxybenzoic acid, such as o-, p-, or m-anisic acid), salicylic acid, phthalic acid, isophthalic acid, terephthalic acid, phenylacetic acid, mandelic acid, 1,2,4-benzenetricarboxylic acid, and/or the like, and combinations thereof.

In some embodiments, the carboxylate use in a heat transfer fluid concentrate in accordance with the present teachings includes a plurality of carboxylates. In some embodiments, the carboxylate includes an aliphatic mono-carboxylate, an aliphatic di-carboxylate, an aromatic mono-carboxylate, an aromatic di-carboxylate, or a combination thereof. In some embodiments, the carboxylate includes one or a plurality of C₆-C₂₀ carboxylates, and each of the one or the plurality of C₆-C₂₀ carboxylates is individually selected from the group consisting of an aliphatic mono-carboxylate, an aliphatic di-carboxylate, an aromatic mono-carboxylate, an aromatic di-carboxylate, and a combination thereof. In some embodiments, the carboxylate includes 2-ethyl hexanoic acid, neodecanoic acid, or a combination thereof.

The concentration of carboxylate may vary depending on the application. In some embodiments, the carboxylate is present in an amount from about 1 wt. % to about 10 wt. % based on the total weight of the heat transfer fluid concentrate. Within this range, the amount can be greater than or equal to about 1.5 wt. %, and, in some embodiments, greater than or equal to about 2 wt. %. Also within this range, the amount may be less than or equal to about 7 wt. % and, in some embodiments, less than or equal to about 5 wt. %.

Heat transfer fluid concentrates in accordance with the present teachings may further include one or a plurality of inorganic phosphates. The inorganic phosphate used in accordance with the present teachings is configured to generate phosphate ions upon dissolution in an aqueous solution. Representative inorganic phosphates for use in accordance with the present teachings include but are not limited to orthophosphates such as phosphoric acid, alkali metal orthophosphates (e.g., sodium orthophosphate, potassium orthophosphate, etc.), other water-soluble alkaline metal phosphate salts, and/or the like, and combinations thereof. In some embodiments, an inorganic phosphate for use in accordance with the present teachings is selected from the group consisting of phosphoric acid, sodium orthophosphate, potassium orthophosphate, sodium pyrophosphate, potassium pyrophosphate, sodium polyphosphate, potassium polyphosphate, sodium hexametaphosphate, potassium hexametaphosphate, and/or the like, and combinations thereof. In some embodiments, the inorganic phosphate includes phosphoric acid and/or one or more additional orthophosphates including but not limited to alkali metal orthophosphates and/or other water-soluble alkaline metal phosphate salts.

The concentration of inorganic phosphate may vary depending on the application. In some embodiments, the phosphate ion concentration in a heat transfer fluid concentrate in accordance with the present teachings ranges from about 0.002 wt. % to about 5 wt. % based on the total weight of the heat transfer fluid. In other embodiments, the phosphate ion concentration ranges from about 0.01 wt. % to about 1 wt. % based on the total weight of the heat transfer fluid. In some embodiments, the inorganic phosphate may be present in the heat transfer fluid concentrate an amount of between about 0.10 wt. % and about 0.60 wt. % based on the total weight of the heat transfer fluid concentrate. Within this range, the amount may be greater than or equal to about 0.11 wt. % and, in some embodiments, greater than or equal to about 0.12 wt. %. Also within this range, the amount may be less than or equal to about 0.45 wt. % and, in some embodiments, less than or equal to about 0.40 wt. %.

Heat transfer fluid concentrates in accordance with the present teachings may further include one or a plurality of azole compounds. Representative azole compounds that may be used in accordance with the present teachings include but are not limited to benzotriazole, tolyltriazole, methyl benzotriazole (e.g., 4-methyl benzotriazole, 5-methyl benzotriazole), butyl benzotriazole, other alkyl benzotriazoles (e.g., alkyl group containing from 2 to 20 carbon atoms), mercaptobenzothiazole, thiazole, imidazole, benzimidazole, indazole, tetrazole, tetrahydrotolyltriazole, tetrahydrogenated benzotriazoles (e.g., 4,5,6,7-tetrahydro-benzotriazole), 4-methyl-1H-benzotriazole, 5-methyl-1H-benzotriazole, tetrahydrobenzotriazole, and/or the like, and combinations thereof. In some embodiments, the azole compound used in a heat transfer fluid concentrate in accordance with the present teachings includes a benzotriazole, a tolyltriazole, or a combination thereof.

Azole compounds used in accordance with the present teachings may be substituted or unsubstituted. Representative substituted azole compounds include but are not limited to substituted thiazoles, substituted imidazoles, substituted indazoles, substituted tetrazoles, and/or the like, and combinations thereof. As used herein, the term “substituted” refers to the optional attachment of one or more substituents onto a backbone structure (e.g., an alkyl backbone, an alkenyl backbone, a heterocyclic backbone, etc.). Representative substituents for use in accordance with the present teachings include but are not limited to hydroxyl, amino (—NH₂, —NHR^(a), —NR^(a)R^(b)), oxy (—O—), carbonyl (—CO—), thiol, alkyl, alkenyl, alkynyl, alkoxy, halo, nitrile, nitro, aryl and heterocyclyl groups. These substituents can optionally be further substituted with 1-3 substituents. Examples of substituted substituents include but are not limited to carboxamide, alkylmercapto, alkylsulphonyl, alkylamino, dialkylamino, carboxylate, alkoxycarbonyl, alkylaryl, aralkyl, alkylheterocyclyl, heterocyclylaryl, haloalkyl, and the like.

The concentration of azole compound may vary depending on the application. In some embodiments, the amount of the azole compound ranges from about 0.01 wt. % to about 3 wt. % based on the total weight of the heat transfer fluid concentrate. Within this range, the azole compound may be present in an amount greater than or equal to about 0.05 wt. % and, in some embodiments, greater than or equal to about 0.1 wt. %. Also within this range, the azole compound may be present in an amount less than or equal to about 2 wt. % and, in some embodiments, less than or equal to about 1 wt. %.

In accordance with the present teachings, heat transfer fluid concentrates include calcium ions. In some embodiments, the calcium ions are derived from one or a plurality of calcium salts (e.g., one or more water-soluble calcium salts). In some embodiments, the calcium ions are derived from one or a plurality of water-soluble calcium salts that are configured to at least partially disassociate in an aqueous solution at room temperature. In some embodiments, the one or the plurality of calcium salts are configured to produce between about 1 and about 60 mg/L calcium ions (Ca²⁺) in the heat transfer fluid concentrate upon dissolution.

Calcium compounds for use in accordance with the present teachings include but are not limited to inorganic calcium compounds and calcium salts of organic acids containing one or a plurality of carboxylic acid groups. Representative inorganic calcium compounds include but are not limited to calcium hydroxide, calcium molybdate, calcium vanadate, calcium tungstate, calcium perchlorate, calcium chloride, and/or the like, hydrates of any of the aforementioned salts, and combinations thereof. Representative calcium salts of organic acids include but are not limited to calcium acetate, calcium formate, calcium propionate, calcium polymaleate, calcium polyacrylate, calcium lactate, calcium gluconate, calcium glycolate, calcium glucoheptonate, calcium citrate, calcium tartrate, calcium glucarate, calcium succinate, calcium hydroxysuccinate, calcium adipate, calcium oxalate, calcium malonate, calcium sulfamate, calcium salts of aliphatic tri-carboxylic acid, calcium salts of aliphatic tetra-carboxylic acid, and/or the like, hydrates of any of the aforementioned calcium salts, and combinations thereof.

In some embodiments, the calcium compound may be a calcium salt formed between calcium ions and a phosphonate or a phosphinate, such as calcium-PBTC salts (where PBTC is 2-phosphonobutane-1,2,4-tricarboxylic acid), calcium-HEDP salts (where HEDP is 1-hydroxethane-1,1-diphosphonic acid), calcium-HPA salts (where HPA is hydroxyphosphono-acetic acid or 2-hydroxy phosphono acetic acid), calcium phosphonosuccinic acid salts, calcium-PSO salts (where PSO is mono-, bis- and oligomeric phosphinosuccinic acid adduct mixtures as described in U.S. Pat. No. 6,572,789 B1), and/or the like, and combinations thereof.

The concentration of calcium ion (Ca²⁺) may vary depending on the application. In some embodiments, one or more calcium compounds present in a heat transfer fluid concentrate are soluble in the heat transfer fluid concentrate. As used herein, the term “soluble” refers to a degree of dissolution such that that no particulate matter remains visible to the naked eye. In some embodiments, the concentration of calcium ion (Ca²⁺) in a heat transfer fluid concentrate in accordance with the present teachings is between about 1 mg/L and about 60 mg/L. In other embodiments, the concentration of calcium ion is between about 3 mg/L and about 40 mg/L. In further embodiments, the concentration of calcium ion is between about 4 mg/L and about 30 mg/L.

Heat transfer fluid concentrates in accordance with the present teachings may further include one or a plurality of water-soluble (polyelectrolyte) polymers.

Illustrative examples of water-soluble polymers suitable for use in a heat transfer fluid concentrate in accordance with the present teachings include water-soluble polymers such as polyelectrolyte dispersants derived from a polymerizable monomer. The polymerizable monomer contains at least one group selected from the group consisting of unsaturated carboxylic acids or salts, unsaturated amides, unsaturated acid anhydrides, unsaturated nitriles, unsaturated carbonyl halides, unsaturated carboxylate esters, unsaturated ethers, unsaturated alcohols, unsaturated sulfonic acids or salts, unsaturated phosphonic acids or salts, unsaturated phosphinic acids or salts, and/or the like, and combinations thereof.

In some embodiments, water-soluble polymers suitable for use in a heat transfer fluid concentrate in accordance with the present teachings include homopolymers, copolymers, terpolymers, and inter-polymers having (1) at least one monomeric unit containing a C₃ to C₁₆ monoethylenically unsaturated mono- or dicarboxylic acid or their alkali metal or ammonium salts; or (2) at least one monomeric unit containing a C₃ to C₁₆ monoethylenically unsaturated mono- or dicarboxylic acid derivative such as an amide, nitrile, carboxylate ester, acid halide (e.g., acid chloride), acid anhydride, and/or the like, and combinations thereof. In some embodiments, a water-soluble polymer suitable for use in accordance with the present teachings may include at least 5% mer units of (1) or (2).

Representative monocarboxylic acids suitable for use in making water-soluble polymers that may be used in a heat transfer fluid concentrate in accordance with the present teachings include but are not limited to acrylic acid, methacrylic acid, ethyl acrylic acid, vinylacetic acid, allylacetic acid, and crotonic acid.

Representative monocarboxylic acid esters suitable for use in making water-soluble polymers that may be used in a heat transfer fluid concentrate in accordance with the present teachings include but are not limited to butyl acrylate, n-hexyl acrylate, t-butylaminoethyl methacrylate, diethylaminoethyl acrylate, hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate, dimethylaminoethyl acrylate, methyl acrylate, methyl methacrylate, tertiary butylacrylate, and vinyl acetate.

Representative dicarboxylic acids suitable for use in making water-soluble polymers that may be used in a heat transfer fluid concentrate in accordance with the present teachings include but are not limited to maleic acid, itaconic acid, fumaric acid, citaconic acid, mesaconic acid, and methylenemalonic acid.

Representative amides suitable for use in making water-soluble polymers that may be used in a heat transfer fluid concentrate in accordance with the present teachings include but are not limited to acrylamide (or 2-propenamide), methacrylamide, ethyl acrylamide, propyl acrylamide, N-t-butylacrylamide, tertiary butyl methacrylamide, tertiary octyl acrylamide, N,N-dimethylacrylamide (or N, N-dimethyl-2-propenamide), dimethylaminopropyl methacrylamide, cyclohexyl acrylamide, benzyl methacrylamide, vinyl acetamide, sulfomethylacrylamide, sulfoethylacrylamide, 2-hydroxy-3-sulfopropyl acrylamide, sulfophenylacrylamide, N-vinyl formamide, N-vinyl acetamide, 2-hydroxy-3-sulfopropyl acrylamide, N-vinyl pyrrolidone (a cyclic amide), 2-vinylpyridene, 4-vinylpyridenem and carboxymethylacrylamide.

Representative anhydrides suitable for use in making water-soluble polymers that may be used in a heat transfer fluid concentrate in accordance with the present teachings include but are not limited to maleic anhydride (or 2,5-furandione) and succinic anhydride.

Representative nitriles suitable for use in making water-soluble polymers that may be used in a heat transfer fluid concentrate in accordance with the present teachings include but are not limited to acrylonitrile and methacrylonitrile.

Representative acid halides suitable for use in making water-soluble polymers that may be used in a heat transfer fluid concentrate in accordance with the present teachings include but are not limited to acrylamidopropyltrimethylammonium chloride, diallyldimethylammonium chloride, and methacrylamidopropyltrimethylammonium chloride.

In some embodiments, a water-soluble polymer for use in a heat transfer fluid concentrate accordance with the present teachings contains at least one monomeric unit selected from the group consisting of allylhydroxypropylsulfonate, AMPS or 2-acrylamido-2-methylpropane sulfonic acid, polyethyleneglycol monomethacrylate, vinyl sulfonic acid, styrene sulfonic acid, acrylamidomethyl propane sulfonic acid, methallyl sulfonic acid, allyloxybenzenesulfonic acid, 1,2-dihydroxy-3-butene, allyl alcohol, allyl phosphonic acid, ethylene glycoldiacrylate, aspartic acid, hydroxamic acid, 2-ethyl-oxazoline, adipic acid, diethylenetriamine, ethylene oxide, propylene oxide, ammonia, ethylene diamine, dimethylamine, diallyl phthalate, 3-allyloxy-2-hydroxy propane sulfonic acid, polyethylene glycol monomethacrylate, sodium styrene sulfonate, an alkoxylated allyl alcohol sulfonate, and/or the like, and combinations thereof.

In some embodiments, the water-soluble polymer suitable for use in a heat transfer fluid concentrate in accordance with the present teachings contains at least 5 mole % of mer units (e.g., as polymerized units) resulting from the polymerization of one or more monomers selected from the group consisting of (a) acrylic acid, methacrylic acid, crotonic acid, vinyl acetic acid, 4-methyl-4 penenoic acid, maleic acid, maleic anhydride, 1,2,3,6-tetrahydrophthalic anhydride, 3,6-epoxy-1,2,3,6-tetrahydrophthalic anhydride, 5-norbornene-2,3-dicarboxylic anhydride, bicycle[2,2,2]-5-octene-2,3-dicarboxylic anhydride, 3-methyl-1,2,6-tetrahydrophthalic anhydride, 2-methyl-1,3,6-tetrahydrophthalic anhydride, itaconic acid, mesaconic acid, methylenemalonic acid, fumaric acid, citraconic acid, 2-acrylamido-2-methylpropanesulfonic acid, 3-allyloxy-2-hydroxy propane sulfonic acid, allyl phosphonic acid, allyloxybenzenesulfonic acid, 2-hydroxy-3-(2-propenyloxy)propanesulfonic acid, allylsulfonic acid, other acrylamidomethyl propane sulfonic acids, methallyl sulfonic acid, isopro-phenylsulfonic acid, vinylphosphonic acid, styrenesulfonic acid, vinylsulfonic acid, aspartic acid, hydroxamic acid, adipic acid, and the alkali metal or ammonium salts of any of the foregoing; (b) methyl acrylate, ethyl acrylate, butyl acrylate, n-hexyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, isobutyl methacrylate, t-butylaminoethyl methacrylate, diethylaminoethyl acrylate, hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate, dimethylaminoethyl acrylate, tertiary butylacrylate, polyethyleneglycol monomethacrylate, phosphoethyl methacrylate, and vinyl acetate; (c) acrylamide (or 2-propenamide), methacrylamide, ethyl acrylamide, propyl acrylamide, N-t-butylacrylamide, tertiary butyl methacrylamide, tertiary octyl acrylamide, N-methylacrylamide, N,N-dimethylacrylamide (or N, N-dimethyl-2-propenamide), dimethylaminopropyl methacrylamide, cyclohexyl acrylamide, benzyl methacrylamide, vinyl acetamide, sulfomethylacrylamide, sulfoethylacrylamide, 2-hydroxy-3-sulfopropyl acrylamide, sulfophenylacrylamide, N-vinyl formamide, N-vinyl acetamide, 2-hydroxy-3-sulfopropyl acrylamide, N-vinyl pyrrolidone (a cyclic amide), 2-vinylpyridene, 4-vinylpyridenem, and carboxymethylacrylamide; (d) maleic anhydride (or 2,5-furandione) and succinic anhydride; acrylonitrile, and methacrylonitrile; (e) acrylamidopropyltrimethylammonium chloride, diallyldimethylammonium chloride, and methacrylamidopropyltrimethylammonium chloride; (f) 1,2-dihydroxy-3-butene, allyl alcohol, ethylene glycoldiacrylate, 2-ethyl-oxazoline, diethylenetriamine, ethylene oxide, propylene oxide, ammonia, styrene, ethylene diamine, dimethylamine, diallyl phthalate, polyethylene glycol monomethacrylate, sodium styrene sulfonate, and an alkoxylated allyl alcohol sulfonate; and (g) combinations thereof.

In some embodiments, a representative alkoxylated allyl alcohol sulfonate monomer for use in preparing a water-soluble polymer in accordance with the present teachings has the following structure (1):

wherein R¹ is a hydroxyl substituted alkyl or alkylene radical having 1 to about 10 carbon atoms, or R¹ is a non-substituted alkyl or alkylene radical having 1 to about 10 carbon atoms, or R¹ is —(CH₂—CH₂—O)_(n)—, —[CH₂—CH(CH₃)—O]_(n)—, or combination thereof; wherein “n” is an integer from about 1 to about 50; wherein R² is H or a lower alkyl (C₁-C₃) group; wherein X, when present, is an anionic radical selected from the group consisting of —SO₃, —PO₃, —PO₄, and —COO; wherein Y, when present, is H or any water-soluble cation or cations which together counterbalance the valance of the anionic radical; and wherein a is 0 or 1. In some embodiments, a=1.

Representative water-soluble polyelectrolyte polymers suitable for use in a heat transfer fluid concentrate in accordance with the present teachings may, in some embodiments, have a molecular weight (MW) ranging from about 200 Daltons to about 200,000 Daltons. In other embodiments, suitable water-soluble polyelectrolyte polymer dispersants have a molecular weight (MW) ranging from about 500 Daltons to about 20,000 Daltons.

Illustrative water-soluble polyelectrolyte polymers suitable for use in a heat transfer fluid concentrate in accordance with the present teachings include but are not limited to polycarboxylates. Representative polycarboxylates include but are not limited to (1) polyacrylic acids or polyacrylates, acrylate-based polymers, copolymers, terpolymers, and quad-polymers such as acrylate/acrylamide copolymers, acrylate/AMPS (acrylamido methylene sulfonic acid or 2-acrylamido-2-methyl-1-propanesulfonic acid) or acrylamidoalkane sulfonic acid copolymers, acrylate/sulfonate copolymers, acrylate/hydroxyalkyl acrylate copolymers, acrylate/alkyl acrylate copolymers, acrylate/AMPS/alkyl acrylamide terpolymers, acrylate/acrylamidoalkane sulfonic acid/styrene sulfonic acid (or water-soluble salts) terpolymers, acrylate/acrylamide/sulfoalkylacrylamide terpolymers, acrylic acid/allyloxy-2-hydroxypropylsulfonic acid (AHPSE)/polyethyleneglycol allyl ether terpolymer, acrylate/methacrylate methyl ester/2-propane-1-sulfonic acid, 2-methyl-, sodium salt/bezenesulfonic acid, 4-[(2-methyl-2-propenyl)oxy]-, sodium salt quad-polymers; (2) polymethacrylic acids or polymethacrylates, methacrylate-based polymers, copolymers, terpolymers, and quad-polymers, where one monomer of the corresponding acrylate-based polymers listed in (1) is replaced by methacrylate or methacrylic acid; (3) polymaleic acid or maleic anhydride polymers, maleic acid based polymers, their copolymers, terpolymers and quad-polymers, where one monomer of the corresponding acrylate-based polymers listed in (1) is replaced by maleic acid or maleic anhydride; (4) polyacrylamides, modified acrylamide-based polymers, and acrylamide-based copolymers, terpolymers and quad-polymers, where one monomer of the corresponding acrylate-based polymers listed in (1) is replaced by acrylamide; (5) sulfonic acid-based copolymers, terpolymers and quad-polymers or their water-soluble salts; phosphonic acid-based copolymers, terpolymers and quad-polymers or their water-soluble salts; phosphinic acid-based copolymers, terpolymers and quad-polymers or their water-soluble salts; (6) vinylpyrrolidone-based homopolymers, and copolymers; (7) alkylene oxide-based copolymers and terpolymers; and combinations comprising one or more of the foregoing.

A water-soluble polymer for use in a heat transfer fluid concentrate in accordance with the present teachings may also be either a polyether polyamino methylene phosphonate as described in U.S. Pat. No. 5,338,477 or a phosphino polyacrylate acid.

Representative examples of commercially available polymers suitable for use as water-soluble polyelectrolyte polymers in a heat transfer fluid concentrate in accordance with the present teachings include but are not limited to (a) the Good-Rite® K-700 series of polymers shown in Table 1 available from Noveon (or Lubrizol), (b) the polymers shown in Table 2 available from AkzoNoble, and (c) the polymers shown in Table 3 available from Dow (Rohm & Haas).

TABLE 1 Representative Good-Rite ® K-700 series of polymers Good-Rite ® Polymer Nominal Technical Chemical Molecular Total Active Data Sheet Type Weight pH Solids Solids K-702 PAA 240,000 2.5 25% 24.70% K-7028 PAA 2,000 3.6 55% 51.70% K-7058 PAA 5,000 2.5 50% 49.20% K-7058N NaPAA 5,000 7 45% 35.70% K-7058D NaPAA 5,000 7.5*  100%**   70% K-7600N NaPAA 60,000 8.2 33% 25.70% K-732 PAA 5,000 2.6 50% 49.50% K-739 NaPAA 5,000 7.5*  100%** 70.10% K-752 PAA 2,000 2.6 63% 62.20% K-759 NaPAA 2,000 7.5*  100%** 71.50% K-765 NaPMAA 30,000 7 30% 24.30% K-766 NaPMAA 5,000 7 40% 30.10% K-776 AA/SA N.P. 4.8 37% 30.60% K-775 AA/SA N.P. 3.5 50%   48% K-781 AA/SA/SS N.P. 2.8 55% 52.80% K-797 AA/SA/SS N.P. 2.7 50% 48.50% K-797D Na(AA/SA/SS) N.P. 8.2*  100%** 74.30% K-798 AA/SA/SS N.P. 2.8 50%   48% K-XP212 Proprietary N.P. 4 40% 39.20% PAA = Polyacrylate NaPAA = Sodium Polyacrylate, NaPMAA = Sodium Polymethacrylate AA = Acrylic Acid, SA = Sulfonic Acid or AMPS, SS = Sodium Styrene Sulfonate “Active Solids” = “Total Solids” − “Counter Ions” (sodium) from post-polymerization neutralization with NaOH *pH of a 1% solution **Includes moisture content N.P. = Not published

TABLE 2 Representative AQUATREAT Industrial Water Treatment Polymers available from AkzoNoble. Product Total Solids pH Mw Polyacrylic Acid AR-4 25 2.1 60000 AR-6 25 2.3 100000 AR-260 50 3.2 2000 AR-602A 50 2.8 4500 AR-900A 50 2.9 2600 AR-921A 50 2.6 3000 AR-935 35 3.5 2500 Sodium Polyacrylate AR-602N 45 7.5 4500 AR-636 45 7.5 5000 AR-900¹ 33 5.5 2600 AR-940¹ 40 8.3 2600 Sodium Polymethacrylate AR-231 30 8.5 6500 AR-232 30 8.5 9500 AR-241 40 7 6500 Copolymer AR-335 49 7.2 3400 AR-540 44 4.3 10000 AR-545 44 4.4 5000 AR-546 37 4.8 9900 min AR-978 42 5 4500 AR-980 41 6.4 2800 Sulfonated Styrene Maleic Anhydride VERSA-TL 3 95 7 20000 VERSA-TL 4 25 7 20000 Notes: AR-335 is polyacrylamide; AR-545 and AR-546 are AA/AMPS copolymers; Aquatreat AR-540 is an Acrylic acid (AA)/2-propenoic acid, 2-methyl, methyl ester/benzenesulfonic acid, 4-[(2-methyl-2-propenyl)oxy]-, sodium salt/2-propene-1-sulfonic acid, 2-methyl-, sodium salt terpolymer. Versa TL-4 = sulfonated styrene/maleic anhydride copolymer. Versa TL-3 is the dry form of Versa TL-4. AR-978 is acrylic acid/maleic acid copolymer. AR-980 is an acrylic acid/maleic acid/Nonionic monomer terpolymer.

TABLE 3 Representative Polymers available from Dow (Rohm & Haas). Molecular Product Name Chemical Nature Weight % Solids pH Polyacrylates Acumer ®1000/ Polyacrylic acid and its Na salts 2,000 47-49 3.2-4.0 Optidose ™ 1000 Acumer 1020 Polyacrylic acid 2,000 39-41 2.1-2.5 Acumer 1100 Polyacrylic acid and its Na salts 4,500 47-49 3.2-4.0 Acumer 1110 Polyacrylic acid and its Na salts 4,500 44-46 6.7 Acumer 1050 Polyacrylic acid and its Na salts 2,000-2,300 47-49 3.2-4.0 Acumer 1510 Na Salt of Polycarboxylate 60,000 24-26 2   Acumer 1808 Na Salt of Polycarboxylate 30,000 21-22 3.5-5.0 Acumer 1850 Na Salt of Polycarboxylate 30,000 29-31  9.0-10.8 Acumer 2000/ Modified Polycarboxylate 4,500 42.5-43.5 3.8-4.6 Optidose 2000 Acumer 2100 Copolymer 11,000 36.5-37.5 4.3-5.3 Acumer 3100/ Carboxylate/Sulfonate/Nonionic 4,500 43-44 2.1-2.6 Optidose 3100 Terpolymer Acumer 4161 Phosphinopolycarboxylic Acid 3,300-3,900 46-48 3.0-3.5 Optidose 4210 Polymaleic Acid   500-1,000 50 1.0-2.0 Acumer 5000 Proprietary Polymer 5,000 44.5-45.5 2.1-2.6 Tamol ®850 Na Salt of Polycarboxylate 30,000 29-31  9.0-10.8 Tamol 731A Maleic Anhydride Na Salt Copolymer 15,000 24-26  9.5-10.5 Tamol 960 Na Salt of Polycarboxylate 5,000 39-41 8-9 Notes: Acumer 2000 and 2100 are carboxylic acid/sulfonic acid copolymers (e.g., AA/AMPS copolymers); Acumer 3100 and Acumer 5000 are acrylic acid/t-butyl acrylamide/2-acrylamido-2-methyl propane sulfonic acid terpolymers. Optidose 1000, 2000 and Optidose 3100 are tagged versions of Acumer 1000, 2000, and 3100, respectively.

In some embodiments, a water-soluble polymer suitable for use in a heat transfer fluid concentrate in accordance with the present teachings is selected from the following commercially-available polymers: (1) polymers available from BASF under the SOKALAN and TAMOL brands, including but not limited to Sokalan CP 9 (maleic acid based polymer), Sokalan CP 10, 10S, 12S (all are acrylate-based polymers), 13S, Sokalan HP 22 G, HP 25, HP 59 and HP165 (polyvinylpyrrolidone), Solakan PA 15, PA 20, PA 25 Cl, PA 30 Cl, PA 40, Sokalan PM 10 I, PM 70, Tamol VS, and other similar products; (2) polymers available from Cytec under the CYANAMER brand including but not limited to P-35, P-70, P-80, A-100L and A-15 (all are acrylate- or acrylamide-based polymers or copolymers) and the like; (3) polymers available from Biolab additives under the BLECLENE and BELSPERSE brands, including but not limited to Beclene 200 (maleic acid homopolymer), 283 (maleic acid terpolymer), 400 (sulfonated phosphino polycarboxylic acid) and 499 (sulfonated phosphono polycarboxylic acid); and Belsperse 161 (phosphino polycarboxylic acid) and 164 (phosphino polycarboxylic acid), and the like and (4) water-soluble polymeric products available from Nalco (e.g., acrylic acid/2-acrylamido-2-methylpropyl sulfonic acid copolymers, polyether polyamino phosphonate as described in U.S. Pat. No. 5,338,477, and acrylic acid/acrylamide/acrylamidomethanesulfonic acid terpolymers), GE Betz (e.g., acrylic acid/polyethyleneglycol allyl ether copolymers, acrylic acid/allyloxy-2-hydroxypropylsulfonic acid (or AHPSE)/polyethyleneglycol allyl ether terpolymers, and acrylic acid/AHPSE copolymers), Chemtreat [e.g., allyoxybenzenesulfonic acid (˜3.5 mole %)/methallyl sulfonic acid (˜2.5 mole %)/methyl methacrylate (13-18 mole %)/acrylic acid (76-81 mole %) quad-polymers], Ciba, SNF Floerger, Rhone-Poulenc, Stockhausen, Hercules, Henkel, Allied Colloids, Hoechst Celanese, Ashland Chemical Company, Kurita Water Industries Ltd, Nippon Shokubai Co., and other suppliers.

Additional water-soluble polymers that may be used in a heat transfer fluid concentrate in accordance with the present teachings include but are not limited to those described in the following U.S. Pat. Nos. 3,085,916; 3,578,589; 3,709,815; 3,806,367; 4,499,002; 4,510,059; 4,532,048; 4,563,284; 4,566,973; 4,566,974; 4,640,793; 4,707,271; 4,762,621; 4,784,774; 4,885,097; 4,952,326; 4,952,327; 5,023,001; 5,658,465; 6,361,768B1; 4,556,493; 4,581,145; 4,457,847; 4,703,092; 4,801,388; 4,919,821; 4,929,425; 5,035,806; 5,049,310; 5,080,801; 5,128,419; 5,167,828; 5,171,459; 5,213,691; 5,216,086; 5,260,386; 5,422,408; 5,403,493; 5,534,611; 5,726,267; 5,736,405; 5,776,875; 5,750,070; 5,788,866; 5,858,244; 5,876,623; 6,005,040; 6,017,994; 6,022,401; 6,153,106; 6,225,430B1; 6,232,419B1; 6,312,644B1; 6,344,531B1; 6,380,431B1; 6,426,383B1; 6,440,327B1; 6,461,518B1; 6,645,428B1; 7,115,254B1; 4,443,340; 4,659,480; 4,659,482; 4,913,822; 4,929,362; 4,929,695; 4,931,206; 4,944,885; 5,030,748; 5,078,891; 5,100,558; 5,102,555; 5,108,619; 5,128,427; 5,139,643; 5,147,555; 5,158,622; 5,158,685; 5,169,537; 5,180,498; 5,194,620; 5,211,845; 5,234,604; 5,248,438; 5,242,599; 5,256,302; 5,264,155; 5,271,847; 5,271,862; 5,282,905; 5,320,757; 5,332,505; 5,342,540; 5,350,536; 5,374,336; 5,378,327; 5,378,372; 5,393,456; 5,445,758; 5,512,183; 5,518,630; 5,527,468; 5,575,920; 5,601,754; 6,228,950B1; 6,444,747B1; 6,641,754B2; 4,517,098; 4,530,766; 4,711,725; 5,055,540; 5,071,895; 5,185,412; 5,223,592; 5,277,823; 5,342,787; 5,395,905; 5,401,807; 5,420,211; 5,451,644; 5,457,176; 5,516,432; 5,531,934; 5,552,514; 5,554,721; 5,556,938; 5,597,509; 5,601,723; 5,658,464; 5,755,972; 5,866,664; 5,929,098; 6,114,294; 6,197,522B1; 6,207,780B1; 6,218,491B1; 6,251,680B1; 6,335,404B1; 6,395,185; 5,023,368; 5,547,612; 5,650,473; 5,654,198; 5,698,512; 5,789,511; 5,866,012; 5,886,076; 5,925,610; 6,040,406; 6,995,120B2; 7,087,189B2; 5,346,626; 5,624,995; 5,635,575; 5,716,529; 5,948,268; 6,001,264; 6,162,391; 6,368,552B1; 6,656,365B2; 6,645,384B1; 5,000,856; 5,078,879; 5,087,376; 5,124,046; 5,153,390; 5,262,061; 5,322,636; 5,338,477; 5,378,368; 5,391,303; 5,407,583; 5,454,954; 5,534,157; 5,707,529; 6,691,715B2; 6,869,998B2; 4,372,870; 5,124,047; 4,797,224; 4,485,223; 5,254,286; 4,460,477; 5,015,390; 4,933,090; 4,868,263; 4,895,664; 4,895,916; 5,000,856; 4,900,451; 4,584,105; 4,872,995; 4,711,726; 4,851,490; 4,849,129; 4,589,985; 4,847,410; 4,657,679; 4,801,387; 4,889,637; 4,604,211; 4,710,303; 4,589,985; 4,324,664; 3,752,760; 4,740,314; 4,647,381; 4,836,933; 4,814,406; 4,326,980; 4,008,164; 5,246,332; and 5,187,238. Additional water-soluble polymers that may be used in a heat transfer fluid concentrate in accordance with the present teachings include but are not limited to those described in the following European patents: EP 0,297,049B1; EP 0360746B1; and EP 0,879,794B1. Additional water-soluble polymers that may be used in a heat transfer fluid concentrate in accordance with the present teachings include but are not limited to those described in the following U.S. patent application publications: 2006/0191852A1; 2005/0202995A1; 2002/0195583A1; 2004/00225093A1; 2005/0009959A1; and 2005/0092211A1.

In some embodiments, the water-soluble polymer used in a heat transfer fluid concentrate in accordance with the present teachings includes an acrylate-based polymer. Representative acrylate-based polymers suitable for use in accordance with the present teachings include but are not limited to acrylate-based homopolymer, acrylate-based copolymer, acrylate-based terpolymer, acrylate-based quad-polymer, and combinations thereof. In some embodiments, the acrylate-based polymer comprises polyacrylate. In some embodiments, to obtain optimal performance, the ratio of active acrylate-based polymer concentration to calcium ion concentration in the heat transfer fluid concentrate is greater than 4 and less than about 110. In some embodiments, the ratio of active acrylate-based polymer concentration to calcium ion concentration in the heat transfer fluid concentrates is greater than about 7 and less than about 80.

The pH of heat transfer fluid is between 6.8 and 9.5. Preferably, the pH of the 50 vol. % aqueous solution of the heat transfer fluid is between 7 and 9.0. In some embodiments, a pH of a heat transfer fluid concentrate in accordance with the present teachings is between about 6.8 and about 9.5. In other embodiments, the pH is between about 7.0 and about 9.0. In some embodiments, the pH of a ready-to-use 50 vol. % aqueous solution of the heat transfer fluid concentrate is between about 6.8 and about 9.5 and, in other embodiments, between about 7.0 and about 9.0.

Heat transfer fluid concentrates in accordance with the present teachings may optionally further include magnesium ions. In some embodiments, the magnesium ions are derived from one or a plurality of magnesium salts (e.g., one or more water-soluble magnesium salts). In some embodiments, the magnesium ions are derived from one or a plurality of water-soluble magnesium salts that are configured to at least partially disassociate in an aqueous solution at room temperature. In some embodiments, the one or the plurality of magnesium salts are configured to produce up to about 80 mg/L magnesium ions in the heat transfer fluid concentrate upon dissolution based on the total weight of the heat transfer fluid concentrate.

Magnesium compounds for use in accordance with the present teachings include but are not limited to inorganic magnesium compounds and magnesium salts of organic acids containing one or a plurality of carboxylic acid groups. Representative inorganic magnesium compounds include but are not limited to magnesium molybdate, magnesium hydroxide, magnesium tungstate, magnesium sulfate, magnesium perchlorate, magnesium chloride, magnesium vanadate, and/or the like, hydrates of any of the aforementioned magnesium salts, and combinations thereof. Representative magnesium salts of organic acids include but are not limited to magnesium formate, magnesium acetate, magnesium propionate, magnesium polyacrylate, magnesium polymaleate, magnesium lactate, magnesium gluconate, magnesium glycolate, magnesium glucoheptonate, magnesium citrate, magnesium tartrate, magnesium glucarate, magnesium succinate, magnesium hydroxysuccinate, magnesium adipate, magnesium oxalate, magnesium malonate, magnesium sulfamate, and/or the like, and combinations thereof.

In some embodiments, the magnesium compound may be a magnesium salt formed between magnesium ions and a phosphonate or a phosphinate, such as magnesium-PBTC salts (where PBTC is 2-phosphonobutane-1,2,4-tricarboxylic acid), magnesium-HEDP salts (where HEDP is 1-hydroxethane-1,1-diphosphonic acid), magnesium-HPA salts (where HPA is hydroxyphosphono-acetic acid or 2-hydroxy phosphono acetic acid), magnesium phosphonosuccinic acid salts, magnesium-PSO salts (where PSO is mono-, bis-, and oligomeric phosphinosuccinic acid adduct mixtures as described in U.S. Pat. No. 6,572,789 B1), and/or the like, hydrates of the aforementioned salts, or combinations thereof.

The concentration of magnesium ion may vary depending on the application. In some embodiments, one or more magnesium compounds present in a heat transfer fluid concentrate are soluble in the heat transfer fluid concentrate. In some embodiments, the concentration of magnesium ion (Mg²⁺) in a heat transfer fluid concentrate in accordance with the present teachings is between about 3 mg/L and about 80 mg/L based on the total weight of the heat transfer fluid concentrate. In other embodiments, the concentration of magnesium ion is between about 2 mg/L and about 35 mg/L. In further embodiments, the concentration of magnesium ion is between about 4 mg/L and about 30 mg/L.

For some of the embodiments in which a heat transfer fluid concentrate in accordance with the present teachings further includes magnesium ions and the water-soluble polymer includes an acrylate-based polymer, the ratio of active acrylate-based polymer stabilizer concentration to magnesium ion concentration is between about 1 and about 25 and, in other embodiments is optionally greater than about 5 and less than about 25. In some embodiments, the heat transfer fluid concentrate includes magnesium ions in a concentration ranging from about 3 mg/L to about 80 mg/L based on the total weight of the heat transfer fluid concentrate, the water-soluble polymer includes an acrylate-based polymer, and a weight ratio of the acrylate-based polymer to the magnesium ions ranges from about 1 to about 25 and, in other embodiments, is greater than about 5 and less than about 25.

Heat transfer fluid concentrates in accordance with the present teachings may optionally further include lithium ions. In some embodiments, the lithium ions are derived from one or a plurality of lithium salts (e.g., one or more water-soluble lithium salts). In some embodiments, the lithium ions are derived from one or a plurality of water-soluble lithium salts that are configured to at least partially disassociate in an aqueous solution at room temperature. In some embodiments, the one or the plurality of lithium salts are configured to produce lithium ion in a concentration ranging from about 0 ppm to about 5000 ppm in the heat transfer fluid concentrate upon dissolution based on the total weight of the heat transfer fluid concentrate.

Lithium compounds for use in accordance with the present teachings include but are not limited to inorganic lithium compounds and lithium salts of organic acids containing one or a plurality of carboxylic acid groups. Representative inorganic lithium compounds include but are not limited to lithium hydroxide, lithium phosphate, lithium borate, lithium perchlorate, lithium sulfate, lithium molybdate, lithium vanadate, lithium tungstate, lithium carbonate, and/or the like, hydrates of any of the aforementioned lithium salts, and combinations thereof. Representative lithium salts of organic acids include but are not limited to lithium acetate, lithium benzoate, lithium polyacrylate, lithium polymaleate, lithium lactate, lithium citrate, lithium tartrate, lithium gluconate, lithium glucoheptonate, lithium glycolate, lithium glucarate, lithium succinate, lithium hydroxyl succinate, lithium adipate, lithium oxalate, lithium malonate, lithium sulfamate, lithium formate, lithium propionate, and/or the like, and combinations thereof.

In some embodiments, the lithium compound may be a lithium salt formed between lithium ions and a phosphonate or a phosphinate, such as lithium-PBTC salts (where PBTC is 2-phosphonobutane-1,2,4-tricarboxylic acid), lithium-HEDP salts (where HEDP is 1-hydroxethane-1,1-diphosphonic acid), lithium-HPA salts (where HPA is hydroxyphosphono-acetic acid or 2-hydroxy phosphono acetic acid), lithium phosphonosuccinic acid salts, lithium-PSO salts (where PSO is mono-, bis-, and oligomeric phosphinosuccinic acid adduct mixtures as described in U.S. Pat. No. 6,572,789 B1), and/or the like, hydrates of the aforementioned salts, or combinations thereof.

The concentration of lithium ion may vary depending on the application. In some embodiments, one or more lithium compounds present in a heat transfer fluid concentrate are soluble in the heat transfer fluid concentrate. In some embodiments, the concentration of lithium ion (Li⁺) in a heat transfer fluid concentrate in accordance with the present teachings is between about 0 ppm and about 5000 ppm based on the total weight of the heat transfer fluid concentrate. Within this range, the lithium ion concentration may be less than about 4000 ppm and, in some embodiments, less than or equal to about 3000 ppm. Also within this range, the lithium ion concentration may be greater than or equal to about 50 ppm and, in some embodiments, greater than or equal to about 200 ppm.

Heat transfer fluid concentrates in accordance with the present teachings may optionally further include one or a plurality of phosphonocarboxylates. Phosphonocarboxylates are phosphonated compounds having the general formula (2) H[CHRCHR]_(n)—PO₃M₂  (2) wherein at least one R group in each unit is a COOM, CH₂OH, sulphono or phosphono group, and the other R group—which may be the same as or different than the first R group—is a hydrogen or a COOM, hydroxyl, phosphono, sulphono, sulphato, C₁₋₇ alkyl, C₁₋₇ alkenyl group or a carboxylate, phosphono, sulphono, sulphato and/or hydroxyl substituted C₁₋₇ alkyl or C₁₋₇ alkenyl group; wherein n is 1 or an integer greater than 1; and wherein each M is hydrogen or an alkali metal ion such as a sodium ion, potassium ion and the like. Furthermore, at least one COOM group will be present in one of the R groups. In some embodiments, the phosphonocarboxylates are phosphonated oligomers or mixture of phosphonated oligomers of maleic acid of the formula (3) H[CH(COOM)CH(COOM)]_(n)—PO₃M₂  (3) wherein n is 1 or an integer greater than 1, and M is a cationic species (e.g., alkali metal cations) such that the compound is water-soluble. Representative phosphonocarboxylates include but are not limited to phosphonosuccinic acid, 1-phosphono-1,2,3,4-tetracarboxybutane, and 1-phosphono-1,2,3,4,5,6-hexacarboxyhexane. The phosphonocarboxylates may be a mixture of compounds having the formula (3) with differing values for “n”. The mean value of “n” may be 1 to 2 or, in some embodiments, 1.3 to 1.5. The synthesis of the phosphonocarboxylates is known and described in U.S. Pat. No. 5,606,105. The phosphonocarboxylates are separate and different from the carboxylates described above.

In a heat transfer fluid concentrate in accordance with the present teachings, a phosphonocarboxylate may optionally be present in an amount ranging from about 10 ppm to about 500 ppm based on the total weight of the heat transfer fluid concentrate. Within this range, the phosphonocarboxylate may be present in an amount greater than or equal to about 20 ppm and, in some embodiments, greater than or equal to about 40 ppm. Also within this range, the phosphonocarboxylate may be present in an amount less than or equal to about 400 ppm and, in some embodiments, less than or equal to about 300 ppm. In some embodiments, a heat transfer fluid concentrate in accordance with the present teachings is free of any phosphonocarboxylate.

Heat transfer fluid concentrates in accordance with the present teachings may optionally further include one or a plurality of phosphinocarboxylates. Phosphinocarboxylates are compounds having the general formula (4) H[CHR¹CHR¹]_(n)—P(O₂M)-[CHR²CHR²]_(m)H  (4) wherein at least one R¹ group in each unit is a COOM, CH₂OH, sulphono or phosphono group and the other R¹ group—which may be the same as or different than the first R¹ group—is a hydrogen or a COOM, hydroxyl, phosphono, sulphono, sulphato, C₁₋₇ alkyl, C₁₋₇ alkenyl group or a carboxylate, phosphono, sulphono, sulphato and/or hydroxyl substituted C₁₋₇ alkyl or C₁₋₇ alkenyl group; wherein n is an integer equal to or greater than 1; and wherein each M is hydrogen or an alkali metal ion such as a sodium ion, potassium ion, and the like. Similarly, at least one R² group in each unit is a COOM, CH₂OH, sulphono or phosphono group and the other R² group—which may be the same as or different than the first R² group—is a hydrogen or a COOM, hydroxyl, phosphono, sulphono, sulphato, C₁₋₇ alkyl, C₁₋₇ alkenyl group or a carboxylate, phosphono, sulphono, sulphato and/or hydroxyl substituted C₁₋₇ alkyl or C₁₋₇ alkenyl group; and wherein m is an integer equal to or greater than 0. Furthermore, at least one COOM group will be present in one of the R¹ and R² groups. Representative phosphinocarboxylates include but are not limited to phosphinicosuccinic acid and water-soluble salts thereof, phosphinicobis(succinic acid) and water-soluble salts thereof, and phosphinicosuccinic acid oligomer and salts thereof as described in U.S. Pat. Nos. 6,572,789 and 5,018,577. The phosphonocarboxylates may be a mixture of compounds having the formula (4) with differing values for “n” and “m”. The phosphinocarboxylates are separate and different from the carboxylates described above.

In a heat transfer fluid concentrate in accordance with the present teachings, a phosphinocarboxylate may optionally be present in an amount ranging from about 10 ppm to about 500 ppm based on the total weight of the heat transfer fluid concentrate. Within this range, the phosphinocarboxylate may be present in an amount greater than or equal to about 20 ppm and, in some embodiments, greater than or equal to 40 ppm. Also within this range, the phosphinocarboxylate may be present in an amount less than or equal to about 400 ppm and, in some embodiments, less than or equal to about 300 ppm. In some embodiments, a heat transfer fluid concentrate in accordance with the present teachings is free of any phosphinocarboxylate.

Heat transfer fluid concentrates in accordance with the present teachings may optionally further include molybdate ions. In some embodiments, the molybdate ions are derived from one or a plurality of salts of molybdic acid (e.g., water-soluble molybdate salts). Representative salts of molybdic acid include alkali metal molybdates, alkaline earth metal molybdates, and combinations thereof. Representative molybdates suitable for use as an optional additive in a heat transfer fluid concentrate in accordance with the present teachings include but are not limited to sodium molybdate, potassium molybdate, calcium molybdate, magnesium molybdate, lithium molybdate, and/or the like, and combinations thereof. In addition, hydrates of alkali metal molybdates and/or alkaline earth metal molybdates (e.g., sodium molybdate di-hydrate) may also be used. In some embodiments, if molybdate ions are optionally present in a heat transfer fluid concentrate in accordance with the present teachings, the molybdate ions are not derived from lithium molybdate, calcium molybdate, and/or magnesium molybdate. In some embodiments, a heat transfer fluid concentrate in accordance with the present teachings does not include lithium molybdate, calcium molybdate, and/or magnesium molybdate.

Heat transfer fluid concentrate in accordance with the present teachings may optionally further include one or more additional components. Representative additional components that may optionally be present in a heat transfer fluid concentrate in accordance with the present teachings include but not limited to colorants, antifoaming agents or defoamers, pH-adjusting agents, phosphonates (e.g., AMP or aminotrimethylene phosphonic acid; HEDP or 1-hydroxy ethylidene-1,1-diphosphonic acid; PBTC or 2-butane phosphono-1,2,4-tricarboxylic acid; PCAM or phosphono carboxylate acid mixture; and/or Bricorr 288, which is a mixture of sodium salts of organophosphonic acid H—[CH(COONa)CH(COONa)]_(n)—PO₃Na₂, where n<5 and n_(mean)=1.4), phosphinates (e.g., PSO or phosphinic acid oligomers, which is a mixture of mono-, bis-, and oligomeric phosphinosuccinic acid adduct), water-soluble molybdate salts, lithium salts, nitrites, biocides, polymer dispersants, scale inhibitors, surfactants, bittering agents, additional corrosion inhibitors, other coolant/antifreeze additives, and/or the like, and combinations thereof. In some embodiments, a heat transfer fluid concentrate in accordance with the present teachings may specifically exclude one or more of these optional additional components.

Representative colorants or dyes suitable for use in a heat transfer fluid concentrate in accordance with the present teachings include but are not limited to “Uranine Yellow,” “Uranine Dye,” “Alizarine Green,” “Chromatint Orange 1735” or “Green AGS liquid” from Abbeys Color Inc., or Chromatech Incorporated, “Chromatint Yellow 0963 Liquid Dye,” “Chromatint Yellow 2741 Liquid Dye,” “Chromatint Green 1572 dye,” “Chromatint Green 2384 Dye,” “Chromatint Violet 1579 Dye” from Chromatech Incorporated, “Acid Red #52” or Sulforhodamine B from Tokyo Chemical Industry Co. or TCI America, “Orange II (acid Orange 7)” or “Intracid Rhodamine WT (Acid Red 388) from Sensient Technologies or other suppliers.

Representative antifoaming agents or defoamers suitable for use in a heat transfer fluid concentrate in accordance with the present teachings include but are not limited to “PM-5150” available from Prestone Products Corp., “Pluronic L-61” from BASF Corp., “Patcote 492” and other Patcote-branded antifoam available from Hydrite Chemical Co. and other suppliers, and “Foam Ban 136B” and other Foam Ban antifoams available from Munzing Chemie GmbH or affiliated companies. The optional antifoam agents may also include polydimethylsiloxane emulsion-based antifoams, including but not limited to PC-5450NF from Performance Chemicals, LLC in Boscawen, N.H.; and CNC antifoam XD-55 NF and XD-56 from CNC International in Woonsocket in RI. In some embodiments, the optional antifoam agents may include a silicone, for example, SAG brand of silicone-based antifoams from Momentive Performance Materials Inc. in Waterford, N.Y., Dow Corning and other suppliers; an ethylene oxide-propylene oxide (EO-PO) block copolymer and a propylene oxide-ethylene oxide-propylene oxide (PO-EO-PO) block copolymer (e.g., Pluronic L61, Pluronic L81, and other Pluronic and Pluronic C products); poly(ethylene oxide) or poly(propylene oxide), for example, PPG 2000 (e.g., polypropylene oxide with an average molecular weight of 2000 Daltons); polydiorganosiloxane-based products (e.g., products containing polydimethylsiloxane (PDMS), and the like); fatty acids or fatty acid esters (e.g., stearic acid, and the like); a fatty alcohol, an alkoxylated alcohol and a polyglycol; a polyether polyol acetate, a polyether ethoxylated sorbital hexaoleate, and a poly(ethylene oxide-propylene oxide)monoallyl ether acetate; a wax, a naphtha, kerosene, and an aromatic oil; and/or the like; and combinations thereof.

Representative biocides suitable for use in a heat transfer fluid concentrate in accordance with the present teachings include but are not limited to various non-oxidizing biocides, such as glutaraldehyde, isothiazolin, 5-chloro-2-methyl-4-isothiazolin-3-one, 2-methyl-4-isothiazolin-3-one, 1,2-benzisothiazolin-3-one, 2,2-dibromo-3-nitrilopropionamide, 2-bromo-2-nitropropane-1,3-diol, methylene bis(thiocynate), terbuthylazine, tetrakis(hydroxymethyl) phosphonium sulphate, and/or the like, and combinations thereof.

Representative pH-adjusting agents suitable for use in a heat transfer fluid concentrate in accordance with the present teachings include but are not limited to alkali or alkaline earth metal hydroxides or oxides (e.g., sodium hydroxide, potassium hydroxide), inorganic phosphates (e.g., sodium phosphate, potassium phosphate, sodium pyrophosphate, and potassium pyrophosphate), and/or the like, and combinations thereof.

Heat transfer fluid concentrates in accordance with the present teachings may optionally further include corrosion inhibitors for copper and copper alloys. Representative copper and copper alloy corrosion inhibitors include but are not limited to compounds containing a 5- or 6-membered heterocyclic ring as the active functional group, wherein the heterocyclic ring contains at least one nitrogen atom (e.g., an azole compound of a type described above). In some embodiments, a copper and copper alloy corrosion inhibitor includes a hydrodrobenzotriazole, such as tetrohydrobenzotriazole (e.g., 4,5,6,7-tetrahydro-benzotriazole), tetrahydrotolytriazole (which may be 4-methyl-1H-benzontriazole, 5-methyl-1H-benzotriazole, and other tetrahydrobenzotriazoles as described in U.S. Pat. No. 8,236,205 B1), and/or the like, and combinations thereof; sodium or potassium salts of the above-mentioned azole compounds, and/or the like, and combinations thereof. The copper and copper alloy corrosion inhibitors may be present in the composition in an amount of about 0.01 wt. % to about 2 wt. %.

Representative non-ionic surfactants suitable for use in a heat transfer fluid concentrate in accordance with the present teachings include but are not limited to fatty acid esters, such as sorbitan fatty acid esters, polyalkylene glycols, polyalkylene glycol esters, copolymers of ethylene oxide (EO) and propylene oxide (PO), polyoxyalkylene derivatives of a sorbitan fatty acid ester, and/or the like, and combinations thereof. In some embodiments, the average molecular weight of the non-ionic surfactants is between about 55 and about 300,000 and, in some embodiments, between about 110 and about 10,000. Representative sorbitan fatty acid esters include but are not limited to sorbitan monolaurate (e.g., sold under the tradename Span® 20, Arlacel® 20, S-MAZ® 20M1), sorbitan monopalmitate (e.g., Span® 40 or Arlacel® 40), sorbitan monostearate (e.g., Span® 60, Arlacel® 60, or S-MAZ® 60K), sorbitan monooleate (e.g., Span® 80 or Arlacel® 80), sorbitan monosesquioleate (e.g., Span® 83 or Arlacel® 83), sorbitan trioleate (e.g., Span® 85 or Arlacel® 85), sorbitan tridtearate (e.g., S-MAZ® 65K), and sorbitan monotallate (e.g., S-MAZ® 90). Representative polyalkylene glycols include but are not limited to polyethylene glycols, polypropylene glycols, and combinations thereof. Representative polyethylene glycols include but are not limited to CARBOWAX™ polyethylene glycols and methoxypolyethylene glycols from Dow Chemical Company (e.g., CARBOWAX PEG 200, 300, 400, 600, 900, 1000, 1450, 3350, 4000 & 8000, etc.) or PLURACOL® polyethylene glycols from BASF Corp. (e.g., Pluracol® E 200, 300, 400, 600, 1000, 2000, 3350, 4000, 6000 and 8000, etc.). Representative polyalkylene glycol esters include but are not limited to mono- and di-esters of various fatty acids, such as MAPEG® polyethylene glycol esters from BASF (e.g., MAPEG® 200 ML or PEG 200 Monolaurate, MAPEG® 400 DO or PEG 400 Dioleate, MAPEG® 400 MO or PEG 400 Monooleate, and MAPEG® 600 DO or PEG 600 Dioleate, etc.). Representative copolymers of ethylene oxide (EO) and propylene oxide (PO) include but are not limited to various Pluronic and Pluronic R block copolymer surfactants from BASF, DOWFAX non-ionic surfactants, UCON™ fluids and SYNALOX lubricants from DOW Chemical. Representative polyoxyalkylene derivatives of a sorbitan fatty acid ester include but are not limited to polyoxyethylene 20 sorbitan monolaurate (e.g., products sold under the tradenames TWEEN 20 or T-MAZ 20), polyoxyethylene 4 sorbitan monolaurate (e.g., TWEEN 21), polyoxyethylene 20 sorbitan monopalmitate (e.g., TWEEN 40), polyoxyethylene 20 sorbitant monostearate (e.g., TWEEN 60 or T-MAZ 60K), polyoxyethylene 20 sorbitan monooleate (e.g., TWEEN 80 or T-MAZ 80), polyoxyethylene 20 tristearate (e.g., TWEEN 65 or T-MAZ 65K), polyoxyethylene 5 sorbitan monooleate (e.g., TWEEN 81 or T-MAZ 81), polyoxyethylene 20 sorbitan trioleate (e.g., TWEEN 85 or T-MAZ 85K), and/or the like, and combinations thereof.

In some embodiments, heat transfer fluid concentrates in accordance with the present teachings may be used in cooling systems and may provide corrosion inhibition properties. In some embodiments, a heat transfer fluid concentrate in accordance with the present teachings contains one or more C₆-C₂₀ mono- and/or di-basic aliphatic or aromatic carboxylic acids or salts thereof, a water-soluble orthophosphate salt or phosphoric acid, a low concentration of a water-soluble calcium salt (e.g., an amount configured to provide calcium ion in a concentration ranging from about 1 mg/L to about 60 mg/L), one or more azole compounds, and at least one or more calcium ion stabilizers selecting from the following: (1) acrylate-based homopolymers, copolymers, terpolymers, quad-polymers, or combinations thereof; (2) optionally one or more components selecting from the following groups: (a) phosphonocarboxylate (e.g., Bricorr 288); (b) phosphinocarboxylate compounds (e.g., PSO); (c) 1,2,3,4-butane tetra-carboxylic acid; (d) aconitic acid; and (e) DC Q1-6083 (e.g., O1.5SiCH2CH2CH2OP(O)(CH3)ONa). In some embodiments, the ratio of active acrylate-based polymer concentration to calcium ion concentration in a heat transfer fluid concentrate in accordance with the present teachings is greater than about 4 and less than about 110. In some embodiments, the pH of a heat transfer fluid concentrate in accordance with the present teachings at 50% concentration is between about 7.2 and about 9.0. In some embodiments, a heat transfer fluid concentrate in accordance with the present teachings is free from silicate, borate, and amines and has a nitrate concentration of less than about 50 ppm as NO₃.

In some embodiments, a heat transfer fluid concentrate in accordance with the present teachings is a single-phase, homogeneous solution at room temperature. In some embodiments, a heat transfer fluid concentrate in accordance with the present teachings is storage stable at a temperature between about −10° C. and +100° C. In some embodiments, a heat transfer fluid concentrate and/or a ready-to-use heat transfer fluid derived therefrom (e.g., by dilution) will meet the properties and performance requirements of ASTM D3306.

In some embodiments, a heat transfer fluid concentrate in accordance with the present teachings may be diluted (e.g., with water) to form a heat transfer fluid. For example, in some embodiments, the heat transfer fluid concentrate may be diluted by about 10 vol. % to about 75 vol. % to form a heat transfer fluid. In some embodiments, the water used for dilution is deionized water as described in Section 4.5 of ASTM D3306-10.

In some embodiments, heat transfer fluid concentrate in accordance with the present teachings may be provided as a commercially available product. In other embodiments, a ready-to-use heat transfer fluid in which the heat transfer fluid concentrate has been pre-diluted to around 50 vol. % with water may be provided as a commercially available product. In preparing a ready-to-use heat transfer fluid by dilution, the optimal level of water added to the heat transfer concentrate at use conditions may be determined by the desired freeze-up, boil-over, and corrosion protection requirements.

Heat transfer fluid concentrate that has not been diluted by adding water is typically not used in an engine cooling system as a heat transfer fluid due to its relatively low heat transfer coefficient (or specific heat), high viscosity, and high freeze point. Thus, heat transfer fluid concentrates may be diluted (e.g., to 40 vol. % to 60 vol. % solutions) by adding water before being used in engine cooling systems as heat transfer fluids. Vehicle manufacturers typically use 50 vol. % heat transfer concentrate diluted by water as factory fill fluid in vehicle cooling systems. Heat transfer fluid products that are pre-diluted by water to contain about 40 vol. % to about 60 vol. % heat transfer fluid concentrate are ready-to-use coolants because no additional water is needed when they are added into a vehicle cooling system.

In a ready-to-use heat transfer fluid, the freezing point depressant may be present in an amount of about 1 wt. % to less than about 90 wt. %, based on the total weight of the ready-to-use heat transfer fluid. Within this range, the amount of the freezing point depressant may be greater than or equal to about 30 wt. %, greater than or equal to about 40 wt. %, greater than or equal to about 50 wt. %, greater than or equal to about 55 wt. %, greater than or equal to about 60 wt. %, greater than or equal to about 70 wt. %, greater than or equal to about 75 wt. %, greater than or equal to about 80 wt. %, greater than or equal to about 85 wt. %, greater than or equal to about 86 wt. %, greater than or equal to about 87 wt. %, greater than or equal to about 88 wt. %, or greater than or equal to about 89 wt. %, but less than about 90 wt. % based on the total weight of the ready-to-use heat transfer fluid. Also, within this range, the amount of the freezing point depressant may be less than or equal to about 30 wt. %, less than or equal to about 40 wt. %, less than or equal to about 50 wt. %, less than or equal to about 55 wt. %, less than or equal to about 60 wt. %, less than or equal to about 70 wt. %, less than or equal to about 75 wt. %, less than or equal to about 80 wt. %, less than or equal to about 85 wt. %, less than or equal to about 86 wt. %, less than or equal to about 87 wt. %, less than or equal to about 88 wt. %, or less than or equal to about 89 wt. %, but more than about 1 wt. % based on the total weight of the ready-to-use heat transfer fluid.

In the ready-to-use heat transfer fluid, the carboxylate may be present in an amount of about 0.5 wt. % to about 8 wt. %, based on the total weight of the ready-to-use heat transfer fluid. Within this range, the amount may be greater than or equal to about 0.6 wt. %, or, in some embodiments, greater than or equal to about 0.7 wt. %. Also within this range, the amount may be less than or equal to about 7 wt. %, or, in some embodiments, less than or equal to about 6 wt. %.

In the ready-to-use heat transfer fluid, the inorganic phosphate may be present in an amount of about 0.05 wt. % to about 0.4 wt. % based on the total weight of the ready-to-use heat transfer fluid. Within this range, the amount may be greater than or equal to about 0.07 wt. %, or, in some embodiments, greater than or equal to about 0.08 wt. %. Also within this range, the amount may be less than or equal to about 0.35 wt. %, or, in some embodiments, less than or equal to about 0.30 wt. %.

In the ready-to-use heat transfer fluid, the azole compound may be present in an amount of about 0.005 wt. % to about 2 wt. %, based on the total weight of the ready-to-use heat transfer fluid. Within this range, the azole compound may be present in an amount greater than or equal to about 0.007 wt. %, or, in some embodiments, greater than or equal to about 0.01 wt. %. Also within this range, the azole compound may be present in an amount less than or equal to about 1.5 wt. %, or, in some embodiments, less than or equal to about 1 wt. %.

In the ready-to-use heat transfer fluid, the calcium compound may be present in an amount such that the ready-to-use heat transfer fluid has a calcium ion concentration of greater than about 0.5 ppm based on the total weight of the ready-to-use heat transfer fluid. Within this range, the amount of calcium ions may be less than about 60 ppm. Also within this range, the amount of calcium ions may be less than or equal to about 40 ppm.

The pH of the ready-to-use heat transfer fluid may be between about 7.0 and about 9.5 at room temperature. Within this range, the pH may be greater than or equal to about 7.5 or, in some embodiments, greater than or equal to about 7.8. Also within this range, the pH may be less than or equal to about 9.0 or, in some embodiments, less than or equal to about 8.8.

A method of preventing corrosion in accordance with the present teachings includes contacting a ready-to-use heat transfer fluid of a type described herein with a heat transfer system. The heat transfer system may include one or a plurality of components made by controlled atmosphere brazing (i.e., CAB). In some embodiments, the heat transfer system may include aluminum.

It is also contemplated that in some applications, such as heavy duty engines, it may be desirable to incorporate one or more additional corrosion inhibitors (e.g., including but not limited to nitrites, molybdates, and/or the like, salts thereof, and combinations thereof).

The ready-to-use heat transfer fluid is further demonstrated by the following non-limiting examples. The following examples illustrate features in accordance with the present teachings, and are provided solely by way of illustration. They are not intended to limit the scope of the appended claims or their equivalents.

Examples

The examples were made using the materials shown in Table 4.

TABLE 4 Materials. Component Description EG Ethylene glycol Na tolyltriazole 50 wt. % solution of sodium tolyltriazole Na hydroxide 50 wt. % solution of sodium hydroxide Neodecanoic acid Neodecanoic acid 2-ethyl hexanoic acid 2-ethyl hexanoic acid PM-5150 An anti-foam EMCO H₃PO₄ A 75 wt. % of H₃PO₄ DI H₂O Deionized water Mg(NO3)₂*6H₂O Hexahydrated magnesium nitrate; (MW = 256.30) Mg(Ac)₂*4H₂O Tetrahydrated magnesium acetoacetate; (MW = 214.45) Ca(Ac)₂*H₂O Tetrahydrated calcium acetoacetate; (MW = 176.18) AR-940 Sodium polyacrylate (MW = 2600) aqueous solution, 40% solid, pH = 8.3 Acumer 3100 AA/AM/AMPS terpolymer, (MW = 4500), 43.5% solid, pH = 2.1-3.0 Acumer 4161 Phosphino polycarboxylic acid, (MW = 3600), 51% solid, pH = 3.3 BTCA 1,2,3,4-butane tetracarboxylic acid SAM H-90 Mixture of 4- and 5-methyl benzotriazole (or tolytriazole), benzotriazole, and tetrahydro tolytriazole in water (Wincom Inc.)

The concentrate compositions shown in Tables 5 and 6 were made by mixing the listed ingredients and less than 0.03 weight percent of a dye. The concentrate was diluted to 25 volume percent with deionized water and 100 ppm of chloride was added. A modified GM9066P test was run on the diluted solution using sand cast aluminum 319 at a temperature of 263±3 degrees Fahrenheit. Results are shown below in Tables 5 and 6.

TABLE 5 Synergistic effect - Ca, Mg, Polymer and PO₄ - Modified GM9066P Test Results for OAT coolants containing phosphate Description Mg and Mg and Mg and Mg and Mg and Polyacrylate Polyacrylate Polyacrylate + Polyacrylate + Polyacrylate + Ca, Ca, only, only, AC 3100 only, AC 3100 only, AC 4161 only, Mg and Mg and Ca only no Ca no Ca no Ca no Ca no Ca Polyacrylate Polyacrylate Coolant ID Comp Comp Ex. 1a Ex. 1c Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7 Ingredients wt % wt % wt % wt % wt % wt % wt % wt % wt % Ethylene Glycol 93.12 92.91 93.48 94.42 93.42 93.43 93.56 93.49 93.48 SAM H-90 Sodium Tolytriazole, 0.47 0.47 0.48 0.48 0.48 0.47 0.48 0.48 0.47 50% Sodium Hydroxide, 2.19 2.28 2.08 2.07 2.07 2.05 2.00 2.03 2.06 50% Potassium Hydroxide, 45% Neo Decanoic Acid 0.96 0.96 0.85 0.90 0.90 0.89 0.86 0.86 0.86 2-Ethyl Hexanoic acid 2.87 2.87 2.56 2.70 2.70 2.68 2.58 2.58 2.58 Dye 0.02 Uranine Yellow Dye, 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 40% PM-5150 0.20 0.20 0.18 0.19 0.19 0.19 0.18 0.18 0.18 H3PO4, 75%. 0.17 0.25 0.26 0.17 0.17 0.17 0.26 0.26 0.25 Mg(NO₃)₂*6H₂O, 0.03 MW = 256.30 Mg(Ac)₂*4H₂O, 0.03 0.03 0.03 0.02 0.02 0.02 MW = 214.45 DI H2O 0.05 0.03 0.03 0.03 0.03 0.02 0.03 0.03 Ca(Ac)₂*H₂O, 0.013 0.002 0.002 MW = 176.18 AR-940, Sodiume 0.06 0.02 0.01 0.04 0.04 0.07 0.07 polyacrylate (MW = 2600) aqueous solution, 40% solid, pH = 8.3 Acumer 3100, 0.01 0.01 AA/AM/AMPS terpolymer, Mw = 4500, 43.5% solid, pH 2.1-3.0 Acumer 4161, 0.02 Phosphino polycarboxylic acid, Mw = 3600, 51% solid, pH 3.3 Bitterant, 40% in Ethylene Glycol Total, % 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 pH @ 50 v % 8.32 8.4 Theorectical Mg 0.0 0.0 34.0 34.0 34.0 28.4 22.7 25.0 24.9 cocnentration, mg/kg Theorectical Ca 0.0 28.7 0.0 0.0 0.0 0.0 0.0 3.5 3.6 cocnentration, mg/kg ppm active 7.1 1.8 1.2 5.6 6.2 11.2 11.2 Polyacrylate/ppm Mg ppm active 0.0 79.6 76.9 Polyacrylate/ppm Ca Storage Stability, >4 weeks >4 weeks >4 weeks >4 weeks >4 weeks 100% Coolant concentrate, 100 C. Storage Stability, <1 week  <2 weeks <2 weeks 50 v % Coolant, 100 C. Modified GM9066P - 25 v % Coolant + 100 ppm Cl, Sand cast Al319, 3.0 L engine; 263 ± 3 F. 1 hr LPR CorrRate, 9.85 9.16 0.44 0.71 0.96 0.43 0.44 0.76 0.60 mpy @ 263 F. ± 3 F. 1 hr Ecorr, V/AgAgCl −0.938 −0.977 −0.883 −0.886 −0.889 −0.856 −0.827 −0.866 −0.858 3 hr LPR CorrRate, 8.97 9.19 0.27 0.27 0.45 0.28 0.52 0.54 0.36 mpy @263 F. ± 3 F. 3 hr Ecorr, V/AgAgCl −0.914 −0.920 −0.836 −0.849 −0.861 −0.817 −0.820 −0.841 −0.834 5 hr LPR CorrRate, 8.43 9.11 0.22 0.30 0.39 0.21 0.41 0.46 0.40 mpy @ 263 F. ± 3 F. 5 hr Ecorr, V/AgAgCl −0.905 −0.904 0.830 −0.827 −0.842 −0.799 −0.831 −0.831 −0.819

TABLE 6 Synergistic effect - Ca, Mg, Polymer and PO4 - Modified GM9066P Test Results for OAT coolants containing phosphate Description Ca and Ca and Ca and Ca and Ca and Polyacrylate Polyacrylate Polyacrylate Polyacrylate Polyacrylate Polyacrylate only Ca only only only only only only Coolant ID Comp Comp Comp Ex. 1a Ex. 1b Ex. 1c Ex. 8 Ex. 9 Ex. 10 Ex. 11 Ex. 12 Ingredients wt % wt % wt % wt % wt % wt % wt % wt % Ethylene Glycol 93.12 92.38 92.91 93.48 93.99 93.99 93.99 93.99 SAM H-90 Sodium 0.47 0.47 0.47 0.47 0.20 0.20 0.20 0.20 Tolytriazole, 50% Sodium 2.19 2.57 2.28 2.04 1.90 1.90 1.90 1.90 Hydroxide, 50% Potassium Hydroxide, 45% Neo Decanoic 0.96 0.95 0.96 0.86 0.77 0.77 0.77 0.77 Acid 2-Ethyl Hexanoic 2.87 2.85 2.87 2.58 2.31 2.31 2.31 2.31 acid Dye 0.02 0.02 Uranine Yellow 0.00 0.00 0.00 0.00 0.00 0.00 Dye, 40% PM-5150 0.20 0.20 0.20 0.18 0.20 0.20 0.20 0.20 H3PO4, 75%. 0.17 0.49 0.25 0.25 0.26 0.26 0.26 0.26 Mg(NO₃)₂*6H₂O, MW = 256.30 Mg(Ac)₂*4H₂O, MW = 214.45 DI H2O 0.05 0.05 0.28 0.22 0.23 0.29 Ca(Ac)₂*H₂O, 0.013 0.013 0.012 0.018 0.012 0.006 MW = 176.18 AR-940, Sodiume 0.07 0.07 0.07 0.13 0.12 0.07 polyacrylate (MW = 2600) aqueous solution, 40% solid, pH = 8.3 Acumer 3100, AA/AM/AMPS terpolymer, Mw = 4500, 43.5% solid, pH 2.1-3.0 Acumer 4161, Phosphino polycarboxylic acid, Mw = 3600, 51% solid, pH 3.3 Bitterant, 40% in 0.01 0.01 0.01 0.01 Ethylene Glycol Total, % 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 pH @ 50 v % 8.26 8.29 8.24 8.22 8.26 Theoretical Mg 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 concentration, mg/kg Theoretical Ca 0.0 0.0 28.7 28.8 27.4 41.0 27.3 13.6 concentration, mg/kg ppm active Polyacrylate/ppm Mg ppm active 0.0 9.7 10.2 12.7 17.6 20.6 Polyacrylate/ppm Ca Storage Stability, >4 weeks >4 weeks >4 weeks >4 weeks 100% Coolant concentrate, 100 C. Storage Stability, >4 weeks >4 weeks >2 weeks >4 weeks >4 weeks 50 v % Coolant, 100 C. Modified GM9066P - 25 v % Coolant + 100 ppm Cl, Sand cast Al319, 3.0 L engine; 263 ± 3 F. 1 hr LPR CorrRate, 9.85 11.87 9.16 1.11 2.96 1.03 5.79 4.57 mpy @ 263 F. ± 3 F. 1 hr Ecorr, −0.938 −0.968 −0.977 −0.848 −0.863 −0.890 −0.951 −0.988 V/AgAgCl 3 hr LPR CorrRate, 8.97 9.19 0.94 2.30 1.35 3.74 7.61 mpy @263 F. ± 3 F. 3 hr Ecorr, −0.914 −0.920 −0.831 −0.812 −0.901 −0.901 −0.948 V/AgAgCl 5 hr LPR CorrRate, 8.43 9.11 1.04 mpy @ 263 F. ± 3 F. 5 hr Ecorr, −0.905 −0.904 −0.828 V/AgAgCl Description Ca, Mg and Ca, Mg and Ca, Mg and Ca, Mg and Ca, Mg and Ca, Mg and Polyacrylate Polyacrylate Polyacrylate Polyacrylate Polyacrylate Polyacrylate Coolant ID Ex. 13 Ex. 14 Ex. 15 Ex. 16 Ex. 17 Ex. 18 Ingredients wt % wt % wt % wt % wt % wt % Ethylene Glycol 93.56 93.99 93.40 93.99 93.99 94.02 SAM H-90 0.10 Sodium 0.20 0.20 0.20 0.20 0.20 Tolytriazole, 50% Sodium 2.10 1.90 1.90 1.90 1.90 1.97 Hydroxide, 50% Potassium Hydroxide, 45% Neo Decanoic 0.86 0.77 0.77 0.77 0.77 0.77 Acid 2-Ethyl Hexanoic 2.58 2.31 2.31 2.31 2.31 2.31 acid Dye Uranine Yellow 0.00 0.00 0.00 0.00 0.00 0.00 Dye, 40% PM-5150 0.20 0.20 0.20 0.20 0.20 0.20 H3PO4, 75%. 0.26 0.26 0.26 0.25 0.26 0.26 Mg(NO₃)₂*6H₂O, MW = 256.30 Mg(Ac)₂*4H₂O, 0.03 0.03 0.02 0.02 0.03 0.02 MW = 214.45 DI H2O 0.14 0.27 0.87 0.27 0.18 0.27 Ca(Ac)₂*H₂O, 0.005 0.005 0.003 0.003 0.005 0.002 MW = 176.18 AR-940, Sodiume 0.06 0.07 0.07 0.07 0.16 0.07 polyacrylate (MW = 2600) aqueous solution, 40% solid, pH = 8.3 Acumer 3100, AA/AM/AMPS terpolymer, Mw = 4500, 43.5% solid, pH 2.1-3.0 Acumer 4161, Phosphino polycarboxylic acid, Mw = 3600, 51% solid, pH 3.3 Bitterant, 40% in 0.01 0.01 0.01 0.01 0.01 Ethylene Glycol Total, % 100.00 100.00 100.00 100.00 100.00 100.00 pH @ 50 v % 8.39 8.27 8.39 8.22 8.24 8.3 Theoretical Mg 34.0 29.5 24.9 24.8 29.5 24.9 concentration, mg/kg Theoretical Ca 11.4 11.4 6.6 5.7 11.4 3.9 concentration, mg/kg ppm active 7.1 9.5 11.2 11.3 21.7 11.2 Polyacrylate/ppm Mg ppm active 21.1 24.6 42.4 49.2 56.3 72.4 Polyacrylate/ppm Ca Storage Stability, >4 weeks >4 weeks >4 weeks >4 weeks >4 weeks >4 weeks 100% Coolant concentrate, 100 C. Storage Stability, >2 weeks >2 weeks >4 weeks >4 weeks >4 weeks >2 weeks 50 v % Coolant, 100 C. Modified 130 ± 2 C. 130 ± 2 C. GM9066P - 25 v % Coolant + 100 ppm Cl, Sand cast Al319, 3.0 L engine; 263 ± 3 F. 1 hr LPR CorrRate, 0.89 1.27 0.51 mpy @ 263 F. ± 3 F. 1 hr Ecorr, −0.859 −0.794 −0.848 V/AgAgCl 3 hr LPR CorrRate, 0.82 1.38 0.51 mpy @263 F. ± 3 F. 3 hr Ecorr, −0.840 −0.758 −0.823 V/AgAgCl 5 hr LPR CorrRate, 0.63 0.50 0.29 mpy @ 263 F. ± 3 F. 5 hr Ecorr, −0.833 −0.816 −0.830 V/AgAgCl

The entire contents of each and every patent and non-patent publication cited herein are hereby incorporated by reference, except that in the event of any inconsistent disclosure or definition from the present specification, the disclosure or definition herein shall be deemed to prevail.

It is to be understood that use of the indefinite articles “a” and “an” in reference to an element (e.g., “a carboxylate,” “an inorganic phosphate,” etc.) does not exclude the presence, in some embodiments, of a plurality of such elements.

The foregoing detailed description has been provided by way of explanation and illustration, and is not intended to limit the scope of the appended claims. Many variations in the presently preferred embodiments illustrated herein will be apparent to one of ordinary skill in the art, and remain within the scope of the appended claims and their equivalents.

It is to be understood that the elements and features recited in the appended claims may be combined in different ways to produce new claims that likewise fall within the scope of the present invention. Thus, whereas the dependent claims appended below depend from only a single independent or dependent claim, it is to be understood that these dependent claims can, alternatively, be made to depend in the alternative from any preceding claim—whether independent or dependent—and that such new combinations are to be understood as forming a part of the present specification. 

The invention claimed is:
 1. A heat transfer fluid concentrate comprising: a freezing point depressant, water, or a combination thereof; a carboxylate; an inorganic phosphate; an azole compound; calcium ions in a concentration ranging from about 1 mg/L to about 60 mg/L based on a total weight of the heat transfer fluid concentrate; and a water-soluble polymer; wherein the heat transfer fluid concentrate is free of calcium molybdate.
 2. The heat transfer fluid concentrate of claim 1 wherein the water comprises de-ionized water, de-mineralized water, softened water, or a combination thereof.
 3. The heat transfer fluid concentrate of claim 1 wherein a hardness of the water due to CaCO₃ is less than about 20 ppm and/or wherein an electrical conductivity of the water is less than about 300 μS/cm.
 4. The heat transfer fluid concentrate of claim 1 wherein the freezing point depressant comprises an alcohol.
 5. The heat transfer fluid concentrate of claim 1 wherein the freezing point depressant is selected from the group consisting of ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, glycerol, and a combination thereof.
 6. The heat transfer fluid concentrate of claim 1 wherein the freezing point depressant comprises from about 15 wt. % to about 99% wt. % based on the total weight of the heat transfer fluid concentrate.
 7. The heat transfer fluid concentrate of claim 1 wherein the freezing point depressant comprises from about 20 wt. % to about 98% wt. % based on the total weight of the heat transfer fluid concentrate.
 8. The heat transfer fluid concentrate of claim 1 wherein the freezing point depressant comprises from about 20 wt. % to about 96% wt. % based on the total weight of the heat transfer fluid concentrate.
 9. The heat transfer fluid concentrate of claim 1 wherein the carboxylate comprises a plurality of carboxylates.
 10. The heat transfer fluid concentrate of claim 1 wherein the carboxylate comprises an aliphatic mono-carboxylate, an aliphatic di-carboxylate, an aromatic mono-carboxylate, an aromatic di-carboxylate, or a combination thereof.
 11. The heat transfer fluid concentrate of claim 1 wherein the carboxylate comprises one or a plurality of C₆-C₂₀ carboxylates, and wherein each of the one or the plurality of C₆-C₂₀ carboxylates is individually selected from the group consisting of an aliphatic mono-carboxylate, an aliphatic di-carboxylate, an aromatic mono-carboxylate, an aromatic di-carboxylate, and a combination thereof.
 12. The heat transfer fluid concentrate of claim 1 wherein the carboxylate comprises 2-ethyl hexanoic acid, neodecanoic acid, or a combination thereof.
 13. The heat transfer fluid concentrate of claim 1 wherein the carboxylate comprises a compound selected from the group consisting of benzoic acid, octanoic acid, heptanoic acid, and a combination thereof.
 14. The heat transfer fluid concentrate of claim 1 wherein the carboxylate comprises from about 1 wt. % to about 10 wt. % based on the total weight of the heat transfer fluid concentrate.
 15. The heat transfer fluid concentrate of claim 1 wherein the inorganic phosphate comprises an orthophosphate, phosphoric acid, or a combination thereof.
 16. The heat transfer fluid concentrate of claim 1 wherein the inorganic phosphate comprises a water-soluble alkaline metal phosphate salt, phosphoric acid, or a combination thereof.
 17. The heat transfer fluid concentrate of claim 1 wherein a phosphate ion concentration in the heat transfer fluid concentrate ranges from about 0.002 wt. % to about 5 wt. % based on the total weight of the ready-to-use heat transfer fluid.
 18. The heat transfer fluid concentrate of claim 1 wherein a phosphate ion concentration in the heat transfer fluid concentrate ranges from about 0.01 wt. % to about 1 wt. % based on the total weight of the ready-to-use heat transfer fluid.
 19. The heat transfer fluid concentrate of claim 1 wherein the azole compound comprises a benzotriazole, a tolyltriazole, or a combination thereof.
 20. The heat transfer fluid concentrate of claim 1 wherein the azole compound comprises from about 0.01 wt. % to about 3 wt. % based on the total weight of the heat transfer fluid concentrate.
 21. The heat transfer fluid concentrate of claim 1 wherein the calcium ions are derived from a water-soluble calcium salt.
 22. The heat transfer fluid concentrate of claim 1 wherein the calcium ions are derived from a water-soluble calcium salt that is configured to at least partially disassociate in an aqueous solution at room temperature.
 23. The heat transfer fluid concentrate of claim 1 wherein the concentration of the calcium ions ranges from about 3 mg/L to about 40 mg/L.
 24. The heat transfer fluid concentrate of claim 1 wherein the concentration of the calcium ions ranges from about 4 mg/L to about 30 mg/L.
 25. The heat transfer fluid concentrate of claim 1 wherein the water-soluble polymer comprises an acrylate-based polymer.
 26. The heat transfer fluid concentrate of claim 1 wherein the water-soluble polymer comprises an acrylate-based homopolymer, an acrylate-based copolymer, an acrylate-based terpolymer, or a combination thereof.
 27. The heat transfer fluid concentrate of claim 1 wherein the water-soluble polymer comprises an acrylate-based polymer, and wherein a ratio of a concentration of the acrylate-based polymer to the concentration of the calcium ions is greater than about 4 and less than about
 110. 28. The heat transfer fluid concentrate of claim 1 wherein the water-soluble polymer comprises an acrylate-based polymer, and wherein a ratio of a concentration of the acrylate-based polymer to the concentration of the calcium ions is greater than about 7 and less than about
 80. 29. The heat transfer fluid concentrate of claim 1 wherein a pH of the heat transfer fluid concentrate is between about 6.8 and about 9.5.
 30. The heat transfer fluid concentrate of claim 1 wherein a pH of the heat transfer fluid concentrate is between about 7.0 and about 9.0.
 31. The heat transfer fluid concentrate of claim 1 further comprising a component selected from the group consisting of colorants, antifoam agents, pH-adjusting agents, water-soluble molybdate salts, lithium salts, phosphonates, phosphinates, biocides, and a combination thereof.
 32. A ready-to-use heat transfer fluid comprising: water; and the heat transfer fluid concentrate of claim 1 in an amount ranging from about 40 vol. % to about 60 vol. % based on a total volume of the ready-to-use heat transfer fluid.
 33. A heat transfer fluid concentrate comprising: a freezing point depressant, water, or a combination thereof, wherein the freezing point depressant comprises from about 15 wt. % to about 99% wt. % based on a total weight of the heat transfer fluid concentrate; a C₆-C₂₀ carboxylate comprising from about 1 wt. % to about 10 wt. % based on the total weight of the heat transfer fluid concentrate, wherein the C₆-C₂₀ carboxylate is selected from the group consisting of an aliphatic mono-carboxylate, an aliphatic di-carboxylate, an aromatic mono-carboxylate, an aromatic di-carboxylate, and a combination thereof; an inorganic phosphate selected from the group consisting of an orthophosphate, phosphoric acid, and a combination thereof, wherein a phosphate ion concentration in the heat transfer fluid concentrate ranges from about 0.002 wt. % to about 5 wt. % based on the total weight of the heat transfer fluid concentrate; an azole compound comprising from about 0.01 wt. % to about 3 wt. % based on the total weight of the heat transfer fluid concentrate; calcium ions in a concentration ranging from about 1 mg/L to about 60 mg/L based on a total weight of the heat transfer fluid concentrate; and an acrylate-based polymer; wherein a ratio of a concentration of the acrylate-based polymer to the concentration of the calcium ions is greater than about 4 and less than about
 110. 34. A method of preventing corrosion in a heat transfer system, the method comprising: contacting at least a portion of the heat transfer system with a ready-to-use heat transfer fluid; wherein the ready-to-use heat transfer fluid comprises: a freezing point depressant, water, or a combination thereof; a carboxylate; an inorganic phosphate; an azole compound; calcium ions in a concentration ranging from about 1 mg/L to about 60 mg/L based on a total weight of the ready-to-use heat transfer fluid; and an acrylate-based polymer; wherein the heat transfer fluid concentrate is free of calcium molybdate.
 35. The method of claim 34 wherein the portion of the heat transfer system comprises a component made by controlled atmosphere brazing.
 36. The method of claim 34 wherein a ratio of a concentration of the acrylate-based polymer to the concentration of the calcium ions in the ready-to-use heat transfer fluid is greater than about 4 and less than about
 110. 